The launch of Socket AM3+ processors with Piledriver microarchitecture inspired many AMD fans. However, until recently we only based our opinion on the results obtained from the top model in the new AMD FX family. Today we are going to make up for this omission and carry out a detailed performance analysis of all Vishera processors with eight, six and four cores.

AMD FX-6300

The six-core Vishera FX-6300 processor can be derived from a fully-functional semiconductor die by disabling one of the four dual-core processor modules. In terms of clock frequencies, this processor is similar to FX-8320. The nominal clock speed of this six-core processor is set at 3.5 GHz, but in case of fewer execution threads it may accelerate to 4.1 GHz. In this case the fewer cores and moderate clock frequencies allowed the manufacturer to set its TDP at less liberal 95 W. however, in the end, the working frequencies of the six-core Vishera processors yield to those of the FX-6200 based on the previous generation Bulldozer microarchitecture.

Disabling two cores in the original die didn’t affect the L3 cache memory size, which is also 8 MB big. However, the L2 cache in FX-6300 is smaller, because in Piledriver microarchitecture (just like in Bulldozer microarchitecture) it is individual for each pair of cores. As you may have guessed, it consists of three 2 MB parts, i.e. equals 6 MB against 8 MB in the eight-core processor.

Another distinguishing feature of the six-core Vishera modification is the lower frequency of the North Bridge integrated into the processor. This unit works at 3.2 GHz in FX-8350 and FX-8320, while in FX-6300 it is 200 MHz slower. It results into slight slowing of the processor memory controller and L3 cache. However, practical tests showed that this frequency difference was not critical.

However, FX-6300 is significantly more affordable than the eight-core processors. it is priced at $132 and is positioned as a direct competitor to the old Intel Core i5-2300.

AMD FX-4300

FX-4300 seems to be the strangest FX processor from the new generation. It costs $122, which is only $10 cheaper than FX-6300, but at the same time it is significantly weaker in terms of technical characteristics. First, it has only four cores, because two dual-core modules out of four are disabled. Second, the L3 cache memory in FX-4300 has also been reduced to only 4 MB instead of 8 MB. As a result, we only get a “half” of the FX-8350, but not at half the price of the flagship product.

The operational frequencies of this processor are also far from impressive. The nominal speed of FX-4300 is 3.8 GHz, which could be accelerated to 4.0 GHz in Turbo mode. The North Bridge in this processor works at 2.0 GHz, just like the one in FX-6300. All this allows the quad-core Vishera to remain within the 95 W TDP, but at the same time it is significantly inferior to the previous generation top quad-core offering, the FX-4170, in technical specifications. The latter works at 200-300 MHz higher clock frequency and features a full-size L3 cache. Therefore, we have big concerns about the advantage of the quad-core Vishera processor over the previous generation quad-core Zambezi.

However, even AMD realizes the weakness of their FX-4300 specifications thus positioning their product against the dual-core Core i3-2120 from Sandy Bridge generation. Moreover, judging by the current prices, it would make more sense to go for a quad-core A10-5800K processor for Socket FM2 platform based on the same Piledriver microarchitecture. It sells at exactly the same price, but has an integrated graphics core and slightly higher clock frequencies.